Transcranial Photobiomodulation to Improve Cognition in Gulf War Illness.
Level 2 - randomized trial
Randomized sham-controlled trial
PubMed 33551948 · doi:10.3389/fneur.2020.574386
What was done
A blinded, randomized, sham-controlled trial evaluated transcranial photobiomodulation (tLED using red/near-infrared wavelengths) in 48 veterans (40 men) with Gulf War Illness. Participants received 15 half-hour sessions of real or sham tLED twice weekly over 7.5 weeks. Both participants and assistants wore goggles to maintain blinding. Neuropsychological tests served as primary outcomes, while psychosocial questionnaires (including PTSD assessments and the SF-36V Plus) were secondary outcomes, evaluated at baseline, 1 week, and 1 month after the 15th treatment.
What was found
In primary analyses of all participants, real tLED significantly improved Digit Span Forwards compared to sham (p < 0.01) and showed a trend for Trails 4 Number/Letter Sequencing (p < 0.10). For secondary outcomes, real tLED showed a trend toward improvement on the SF-36V Plus Physical Component Score (p < 0.08). In secondary analyses of participants scoring below the 50th percentile at baseline, both groups improved at 1 week, but at 1 month only the real group showed continued gains across multiple tests (Digit Span Total, Forwards, and Backwards; Trails 4; California Verbal Learning Test-II long delay recall; Continuous Performance Test-II false alarm rate; Stroop Trial 3 Inhibition) and continued PTSD reduction, while the sham group regressed.
Why it matters
This study provides preliminary clinical trial evidence that non-invasive transcranial photobiomodulation may improve aspects of working memory and executive function in veterans suffering from Gulf War Illness.
Limits
The study was underpowered (n = 48) with high baseline heterogeneity, predominantly male participants (40 of 48), and primary analyses achieved significance on only one cognitive test, with broader benefits emerging only in secondary subgroup analyses.
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